Severe water shortages have become an increasing occurrence, particularly in the southwest and western states of the United States, and a hindrance to the development of commercial and residential properties. An unrelated problem with the use of slab building foundations, a very common building technique involving securing a residence or other structure on top of a horizontal slab of reinforced concrete, is the damage caused to the foundation and the supported structure by expanding and contracting subsoil due to variations in the subsoil moisture content throughout the year. Insect infestations are also the scourge of property owners, particularly in the southern states, and range from termite invasion of wooden above-ground structures by way of nests located in the subsurface below the structure to grub worm and fire ant infestations in lawns. Lawn diseases such as brown patch can also wreak havoc on landscapes if left untreated. All of these seemingly unrelated problems are addressed and managed by the gray water recycling system of the present invention. In fact, in many communities facing severe water shortages the use of potable water to stabilize building foundations and irrigate landscapes is prohibited or severely restricted. However, a gray water recycling system would not be subject to such water control programs.
The present invention permits the recycling of gray water in various unique applications with resulting diverse benefits. By way of explanation, effluent discharged from a residence is typically classified as black water or gray water. Black water refers to water drained from sources likely to include fecal matter, grease, and high levels of bacteria, such as toilets, dishwashers, and garbage disposals. Gray water is effluent obtained from sources not likely to contain grease, fecal matter or other high concentrations of bacteria, such as bathtubs, showers, laundry washers, lavatory sinks, and the condensate drain from air conditioning units. Gray water normally contains small amounts of soap and detergent and is generally safe for reuse in applications where clean, potable water is unnecessary.
Prior art gray water recycling systems typically separate the black water and gray water effluent streams. The black water is directed to a septic tank or other sewage treatment. The gray water is then routed back to residential toilets or used in landscape irrigation, thus saving on costs associated with treating the water to a potable state and avoiding the need for obtaining potable water from other sources.
The present invention involves recycling gray water in order to obtain substantially more benefits than merely watering landscape or use in residential toilets. One aspect of the present invention involves the use of the gray water effluent along with a foundation irrigation system to maintain a constant subsoil moisture level in expansive soil. This aspect of the invention protects slab foundations in expansive soil from shifting and cracking, therefore maintaining the integrity of the supported structure. The present invention incorporates an external fluid injection capability into the foundation irrigation stream that also allows for the introduction of pesticides into the subsoil under the slab foundation. This aspect of the invention is ideal for the treatment of termites and other subsoil insect infestations and eliminates the need for the present costly methods of treating for such insects in similar structures by drilling vertically through the foundation and injecting chemicals into the subsoil. The present invention also allows for additives to a gray water stream prior to use of the gray water for landscape irrigation purposes. This additive could be a fertilizer, fungicide, or a pesticide, depending on the application required.
The incorporation and all of these benefits of the present invention can occur in either a micro application for an individual residence or a macro application for an entire development.
As will be described in more detail below, the gray water recycling system invention disclosed allows for a flexible and varied approach to several problems facing property owners and managers while additionally promoting the recycling of a scarce natural resource.